God gives His people gifts and the gift to help others receive their healing is one of these. In my experience, it's not all that unusual. People get healed all the time in our church and when we beleivers pray over the sick. It can be a group of believers who minister God's healing power to an individual. It happens when God's power flows through the medium of willing believers. We are after all his hands and feet in this world. He works through us.
Many times, however, people receive their healing but after a period of time, they lose it and get sick again. This happens because they don't have a firm foundation on God's will for their lives to be well and prosperous body, soul, and mind and so when the adversary or their own minds tells them that perhaps they weren't healed at all or some such lie, they easily succumb to the lie. The faith of other believers can help you get healed but ultimately to hold on to the healing and divine health, you'll need to use your own faith. And that takes being rooted in God's word.